Methods for embedding and extracting a watermark in a text document and devices thereof

Abstract

Method, apparatus and non-transitory computer readable medium for embedding and extracting a watermark in a text document using digital watermarking processes is disclosed. When the text document is watermarked, the following steps are performed. The pages of the text document are transformed into corresponding images. Then, the margins on each of the images are detected and cropped to generate the cropped images. The cropped images are segmented into blocks among which some blocks are selected based on content of each block. The watermark is embedded in the selected blocks using a digital watermarking process. When the watermark from the watermarked text document is extracted, the watermark-embedding process is referred to determine the block information, for selecting each block of a watermarked text document, from where the watermark needs to be extracted.

What is claimed is: 
     
         1 . A method for embedding a watermark in a text document, the method comprising:
 receiving, by a watermark management computing device, a watermark and the text document comprising of one or more pages;   transforming, by the watermark management computing device, the one or more pages of the text document into one or more corresponding images;   detecting, by the watermark management computing device, one or more margins on each of the one or more images;   generating, by the watermark management computing device, one or more cropped images wherein the cropped images are generated by cropping the detected one or more margins from each of the one or more images;   segmenting, by the watermark management computing device, each of the one or more cropped images into a plurality of blocks;   selecting, by the watermark management computing device, one or more blocks from the plurality of blocks based on content of each of the plurality of blocks; and   embedding, by the watermark management computing device, the watermark in each of the selected one or more blocks using a watermarking process.   
     
     
         2 . The method of  claim 1 , where in the method further comprising:
 superimposing, by the watermark management computing device, the watermark embedded blocks onto the corresponding one or more images; and   converting, by the watermark management computing device, the one or more images into the corresponding one or more pages of the text document.   
     
     
         3 . The method of  claim 1 , wherein detecting of the one or more margins comprises:
 using, by the watermark management computing device, a discrete differentiation operator over the one or more images; and   computing, by the watermark management computing device, a distance of a first white pixel from one or more sides of the one or more images.   
     
     
         4 . The method of  claim 3 , wherein generating the one or more cropped images from the corresponding one or more images comprises:
 cropping, by the watermark management computing device, the one or more images from the sides based on the computed distance of the first white pixel from the one or more sides of the image.   
     
     
         5 . The method of  claim 1 , wherein selecting one or more blocks from the plurality of blocks comprises:
 applying, by the watermark management computing device, a discrete cosine transform (DCT) on each of the plurality of blocks to compute a DCT co-efficient of the one or more blocks;   classifying, by the watermark management computing device, the plurality of blocks into texture blocks or non-texture blocks using the DCT co-efficient of each of the one or more blocks; and   selecting, by the watermark management computing device, the texture blocks for embedding the watermark.   
     
     
         6 . The method of  claim 5 , wherein classifying the plurality of blocks comprises:
 comparing, by the watermark management computing device, the DCT co-efficient of each of the one or more block with a content thresholds of the block.   
     
     
         7 . The method as claimed in  claim 1 , wherein the watermarking process is either an image or a video watermarking process. 
     
     
         8 . A method for extracting a watermark from a watermarked text document, the method comprising:
 receiving, by a watermark management computing device, the watermarked text document comprising of one or more pages and block information, wherein the block information comprises segmentation process details such as block size, a original cropped image size and a content thresholds;   converting, by the watermark management computing device, the one or more pages into corresponding one or more images;   detecting, by the watermark management computing device, one or more margins on each of the one or more images;   generating, by the watermark management computing device, one or more cropped images wherein the cropped images are generated by cropping the detected one or more margins from each of the one or more images;   resizing, by the watermark management computing device, the one or more cropped images based on the original cropped image size;   segmenting, by the watermark management computing device, each of the one or more resized cropped images into a plurality of blocks wherein the segmentation of the cropped images is based on the block size;   selecting, by the watermark management computing device, one or more blocks from the plurality of blocks based on the content thresholds; and   extracting, by the watermark management computing device, the watermark from each of the selected one or more blocks.   
     
     
         9 . The method of  claim 8 , wherein detecting of the one or more margins comprises:
 using, by the watermark management computing device, a discrete differentiation operator over the one or more images; and   computing, by the watermark management computing device, a distance of a first white pixel from one or more sides of the one or more images.   
     
     
         10 . The method of  claim 9 , wherein generating the one or more cropped images from the corresponding one or more images comprises:
 cropping, by the watermark management computing device, the one or more images from the sides based on the computed distance of the first white pixel from the one or more sides of the image.   
     
     
         11 . The method of  claim 8 , wherein resizing of the one or more cropped images is based on interpolation process. 
     
     
         12 . The method of  claim 8 , wherein selecting one or more blocks from the plurality of blocks comprises:
 applying, by the watermark management computing device, a discrete cosine transform (DCT) on each of the plurality of blocks to compute a DCT co-efficient of the one or more blocks;   classifying, by the watermark management computing device, the plurality of blocks into texture blocks or non-texture blocks using the DCT co-efficient of each of the one or more blocks wherein the plurality of blocks are classified by comparing the DCT co-efficient of each of the one or more blocks with the content thresholds; and   selecting, by the watermark management computing device, the texture blocks for embedding the watermark.   
     
     
         13 . A watermark management computing device comprising:
 a processor; and   a memory coupled to the processor which is configured to be capable of executing programmed instructions comprising and stored in the memory to:
 receive a watermark and the text document comprising of one or more pages; 
 transform the one or more pages of the text document into one or more corresponding images; 
 detect one or more margins on each of the one or more images; 
 generate one or more cropped images wherein the cropped images are generated by cropping the detected one or more margins from each of the one or more images; 
 segment each of the one or more cropped images into a plurality of blocks; 
 select one or more blocks from the plurality of blocks based on content of each of the plurality of blocks; and 
 embed the watermark in each of the selected one or more blocks using a watermarking process. 
   
     
     
         14 . The watermark management computing device of  claim 13 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions further comprising and stored in the memory to:
 superimpose the watermark embedded blocks onto the corresponding one or more images; and   convert the one or more images into the corresponding one or more pages of the text document.   
     
     
         15 . The watermark management computing device of  claim 13 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the detecting further comprising and stored in the memory to:
 use a discrete differentiation operator over the one or more images; and   compute a distance of a first white pixel from one or more sides of the one or more images.   
     
     
         16 . The watermark management computing device of  claim 15 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the generating the one or more cropped images from the corresponding one or more images further comprising and stored in the memory to:
 crop the one or more images from the sides based on the computed distance of the first white pixel from the one or more sides of the image.   
     
     
         17 . The watermark management computing device of  claim 13 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the selecting one or more blocks from the plurality of blocks further comprising and stored in the memory to:
 apply a discrete cosine transform (DCT) on each of the plurality of blocks to compute a DCT co-efficient of the one or more blocks;   classify the plurality of blocks into texture blocks or a non-texture blocks using the DCT co-efficient of each of the one or more blocks; and   select the texture blocks for embedding the watermark.   
     
     
         18 . The watermark management computing device of  claim 17 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the classifying the plurality of blocks further comprising and stored in the memory to:
 compare the DCT co-efficient of each of the one or more block with a content thresholds of the block.   
     
     
         19 . The watermark management computing device of  claim 13 , wherein the watermarking process is either an image or video watermarking process. 
     
     
         20 . A watermark management computing device comprising:
 a processor; and   a memory coupled to the processor which is configured to be capable of executing programmed instructions comprising and stored in the memory to:
 receive the watermarked text document comprising of one or more pages and block information, wherein the block information comprises segmentation process details such as block size, an original cropped image size and a content thresholds; 
 convert the one or more pages into corresponding one or more images; 
 detect one or more margins on each of the one or more images; 
 generate one or more cropped images wherein the cropped images are generated by cropping the detected one or more margins from each of the one or more images; 
 resize the one or more cropped images based on the original cropped image size; 
 segment each of the one or more resized cropped images into a plurality of blocks wherein the segmentation of the cropped images is based on the segmentation process details; 
 select one or more blocks from the plurality of blocks based on the content thresholds; and 
 extract the watermark from each of the selected one or more blocks. 
   
     
     
         21 . The watermark management computing device of  claim 20 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the detecting of the one or more margins further comprising and stored in the memory to:
 use a discrete differentiation operator over the one or more images; and   compute a distance of a first white pixel from one or more sides of the one or more images.   
     
     
         22 . The watermark management computing device of  claim 21 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the generating the one or more cropped images from the corresponding one or more images further comprising and stored in the memory to:
 crop the one or more images from the sides based on the computed distance of the first white pixel from the one or more sides of the image.   
     
     
         23 . The watermark management computing device of  claim 20 , wherein resizing of the one or more cropped images is based on interpolation process. 
     
     
         24 . The watermark management computing device of  claim 20 , wherein the processor coupled to the memory is further configured to be capable of executing the programmed instructions for the selecting one or more blocks from the plurality of blocks further comprising and stored in the memory to:
 apply a discrete cosine transform (DCT) on each of the plurality of blocks to compute a DCT co-efficient of the one or more blocks;   classify the plurality of blocks into texture blocks or a non-texture blocks using the DCT co-efficient of each of the one or more blocks wherein the plurality of blocks are classified by comparing the DCT co-efficient of each of the one or more blocks with the content thresholds; and   select the texture blocks for embedding the watermark.   
     
     
         25 . A non-transitory computer readable medium having stored thereon instructions for embedding a watermark in a text document which when executed by a processor, cause the processor to perform steps comprising:
 receiving a watermark and the text document comprising of one or more pages;   transforming the one or more pages of the text document into one or more corresponding images;   detecting one or more margins on each of the one or more images;   generating one or more cropped images wherein the cropped images are generated by cropping the detected one or more margins from each of the one or more images;   segmenting each of the one or more cropped images into a plurality of blocks;   selecting one or more blocks from the plurality of blocks based on content of each of the plurality of blocks; and   embedding the watermark in each of the selected one or more blocks using a watermarking process.   
     
     
         26 . A non-transitory computer readable medium having stored thereon instructions for extracting a watermark from a watermarked text document which when executed by a processor, cause the processor to perform steps comprising:
 receiving a watermarked text document comprising of one or more pages and block information, wherein the block information comprises segmentation process details such as block size, an original cropped image size and a content thresholds;   converting the one or more pages into corresponding one or more images;   detecting one or more margins on each of the one or more images;   generating one or more cropped images wherein the cropped images are generated by cropping the detected one or more margins from each of the one or more images;   resizing the one or more cropped images based on the original cropped image size;   segmenting each of the one or more resized cropped images into a plurality of blocks wherein the segmentation of the cropped images is based on the block size;   selecting one or more blocks from the plurality of blocks based on the content thresholds; and   extracting the watermark from each of the selected one or more blocks.